1. Field of the Invention
The present invention relates to an image input apparatus, an image processing apparatus, an image input method, an image processing method and an image input system, and more particularly to an image input apparatus and an image input system having an image compressing function.
2. Related Background Art
FIG. 18 is a view schematically showing a conventional image reading system, wherein a host computer (hereinafter simply called host) 11xe2x80x2 is loaded with a scanner driver for driving an image scanner (hereinafter simply called scanner) constituting an image reading apparatus, and with various application softwares. A scanner 12xe2x80x2 under the control of the scanner driver converts an optical image into an electrical signal, then digitizes the signal by an unrepresented A/D (analog-to-digital) converter followed by image processing, and transfers the signal through a predetermined interface (e.g., SCSI or USB) to the host computer 11xe2x80x2.
On the other hand, owing to the recent progress in the high efficiency image encoding technology, the image information is commonly compressed in storage by a host computer or a personal computer (PC).
However, the scanners are becoming capable of reading the image with a high resolution such as 1200 dpi (dpi=dots per inch), resulting in an enormous amount of information to be transferred to the host computer with a long transfer time, leading to deterioration of convenience for the user.
It is therefore conceivable to transfer the image, compressed in the scanner, to the computer, but it is necessary to consider convenience of handling in the scanner and in the computer. Particularly in case of sub-band encoding such as discrete wavelet transformation, it is necessary, depending on the depth of level of sub-band encoding, to determine each time the level of decoding when an image of a certain size and a certain resolution is required in the host computer or in the scanner, so that the handling is rather difficult.
Also in executing such sub-band encoding, the high efficiency encoding itself of the image may become unable to improve the compression rate or may result in a deterioration of the image even if the number of sub-band levels is increased, if the sub-band encoding is executed uniformly to a certain predetermined level.
In consideration of the foregoing, the object of the present is to provide an image input apparatus, an image processing apparatus etc. allowing to improve the convenience of handling of the image data after the sub-band encoding.
The above-described object can be attained, according to a preferred embodiment of the present invention, namely an image input apparatus comprising: a photoelectric conversion means for converting an optical image into a digital image; an encoding means for sub band encoding the digital image; a designation means for designating the resolution of the digital image; and a control means for determining the number of levels of the sub band encoding according to the designated resolution.
The above-described object can be also attained, according to a preferred embodiment of the present invention, namely an image input apparatus comprising: a photoelectric conversion means for converting an optical image into a digital image; an encoding means for sub band encoding the digital image; a designation means for designating the size of the input optical image; and a control means for determining the number of levels of the sub band encoding according to the designated size.
The above-described configurations allow, in inputting an image of any resolution, to easily decode the sub-band encoded image to obtain an image not much different in resolution, whereby the handling of the image signal after encoding can be facilitated.
Other objects of the present invention, and the features thereof, will become fully apparent from the following description of embodiments, to be taken in conjunction with the accompanying drawings.